There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)

Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:

You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).

If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.

And apparently the sky is falling. From Ittay Eyal and Emin Gün Sirer at Hacking, Distributed:

But the fact is, this is a monumental event. The Bitcoin narrative, based on decentralization and distributed trust, is no more. True, the Bitcoin economy is about as healthy as it was yesterday, and the Bitcoin price will likely remain afloat for quite a while. But the Bitcoin economy and price are trailing indicators. The core pillar of the Bitcoin value equation has collapsed.

Their proposal is a hard fork, with different parameters (to make huge mining pools no longer an economically rational choice), but respecting the blockchain to date so they can reasonably keep calling it "Bitcoin".

I believe our approach is justified, and in order to explain why – consistent with the project of laying out the basic worldview and epistemology behind our research – I find myself continually returning to the distinction between what I call “sequence thinking” and “cluster thinking.” Very briefly (more elaboration below),

Sequence thinking involves making a decision based on a single model of the world: breaking down the decision into a set of key questions, taking one’s best guess on each question, and accepting the conclusion that is implied by the set of best guesses (an excellent example of this sort of thinking is Robin Hanson’s discussion of cryonics). It has the form: “A, and B, and C … and N; therefore X.” Sequence thinking has the advantage of making one’s assumptions and beliefs highly transparent, and as such it is often associated with finding ways to make counterintuitive comparisons.

Cluster thinking – generally the more common kind of thinking – involves approaching a decision from multiple perspectives (which might also be called “mental models”), observing which decision would be implied by each perspective, and weighing the perspectives in order to arrive at a final decision. Cluster thinking has the form: “Perspective 1 implies X; perspective 2 implies not-X; perspective 3 implies X; … therefore, weighing these different perspectives and taking into account how much uncertainty I have about each, X.” Each perspective might represent a relatively crude or limited pattern-match (e.g., “This plan seems similar to other plans that have had bad results”), or a highly complex model; the different perspectives are combined by weighing their conclusions against each other, rather than by constructing a single unified model that tries to account for all available information.

A key difference with “sequence thinking” is the handling of certainty/robustness (by which I mean the opposite of Knightian uncertainty) associated with each perspective. Perspectives associated with high uncertainty are in some sense “sandboxed” in cluster thinking: they are stopped from carrying strong weight in the final decision, even when such perspectives involve extreme claims (e.g., a low-certainty argument that “animal welfare is 100,000x as promising a cause as global poverty” receives no more weight than if it were an argument that “animal welfare is 10x as promising a cause as global poverty”).

Finally, cluster thinking is often (though not necessarily) associated with what I call “regression to normality”: the stranger and more unusual the action-relevant implications of a perspective, the higher the bar for taking it seriously (“extraordinary claims require extraordinary evidence”).